This invention relates generally to electricity metering and more particularly, to an electronic electricity meter configurable to operate in a plurality of meter forms and ratings.
Since data collected from metering electric services within an electric distribution network is used for billing customers, the collected data must be accurate. To ensure accuracy, and in the past, different meter forms are used to meter energy consumption for different types of electric services and load ranges. Specifically, within an electric distribution network of a utility, there are many different services and loads which a utility desires to meter. Each type of service and load may require a meter having a particular xe2x80x9cformxe2x80x9d and xe2x80x9cratingxe2x80x9d. The term xe2x80x9cformxe2x80x9d as used in the art refers to the physical configuration of an electrical service, and the term xe2x80x9cratingxe2x80x9d refers to both voltage and current range.
From application to application, the form and rating of the electricity meter required to accurately meter energy consumption may vary. Although broad current range and wide voltage range meters have reduced the number of different meter types required for such metering applications, meters having many different forms and ratings are still required by each utility.
Of course, requiring a utility to have on hand meters with a number of different forms and ratings results in increasing the costs associated with providing electric service. Particularly, different form and rated meters typically are stored in inventory so that when a metering application is identified which requires a particular form and rated meter, the meter is readily available and can be installed. In addition to the inventory costs, utility personnel must be trained on installation of each different form and rated meter. Of course, requiring skilled workers trained in the installation of a wide variety of meter types to install the meters also is costly.
It would be desirable to provide one meter capable of being used in a plurality of different applications requiring different forms and ratings to facilitate reducing the inventory and labor costs associated with metering a wide variety of electrical services. It also would be desirable to provide such a meter which does not adversely impact the accuracy of the energy measurements made.
These and other objects may be attained by an electricity meter which, in one embodiment, a digital signal processor configurable for generating energy measurements for a plurality of meter form types and connections. More particularly, and in the one embodiment, the meter includes voltage and current sensor for generating signals representative of current and voltage at a load, and the digital signal processor (DSP) is coupled to the voltage and current sensors. The DSP includes a memory, and a plurality of selectable instruction sets corresponding to respective meter form types are stored in the DSP memory. The form types includes meter ANSI form 9 and meter ANSI form 16 type forms, and the instruction sets include processing steps to be executed to determine line voltages and line currents for respective meter form types.
The meter also includes a microcomputer coupled to the DSP for receiving data generated by the DSP. The microcomputer is operable to transmit a selection command to the DSP to control selection of one of the instruction sets stored in the DSP memory. An optical port may be electrically coupled to the microcomputer; and the microcomputer is configured to receive a control command from the optical port. The microcomputer uses the control command to generate the selection command.
When fabricating the above described meter, a meter base is selected to at the factory. As is known in the art, and by way of example with respect to meter socket types, the meter base configuration may conform to the ANSI 9S socket configuration or the ANSI 16S socket configuration. With respect to bottom connected meter types, the meter base configuration may conform to ANSI 10A, 48A or 16A configurations. Depending on the meter base configuration, the DSP memory is then loaded with instruction sets for all possible applications for that particular base. For example, a meter having a base, which conforms to an ANSI 9S socket, may have a 3 element, a 2xc2xd element, a 2 element, or a 1 element connection between the meter and the power lines. In addition, and for each of the various number of elements, the specific electric circuit to which meter is actually is used depends upon the electric service, e.g., an ANSI 9S form may be electrically connected to a 4W-Y electrical connection, a 4W-xcex94 electrical connection, a 3W-xcex94 electrical connection, a 3Wxe2x88x921"PHgr" electrical connection, and a 2Wxe2x88x921"PHgr" electrical connection. Alternatively, the electric meter may be connected to an ANSI 16S form electric service, where the three element connection may be electrically connected to a 4W-Y electrical connection, a 4W-xcex94 electrical connection, a 3W-xcex94 electrical connection, a 3W-Network electrical connection, a 3Wxe2x88x921"PHgr" electrical connection, and a 2Wxe2x88x921"PHgr" electrical connection. All the instruction sets for the various meter forms reside in the DSP ROM memory, and the instruction sets contain the process steps to be executed for each of the possible applications for the particular meter base. The meter is preprogrammed at the factory so that the most commonly used instruction set for the meter base is selected for execution by the DSP, and the meter is then delivered to the utility.
At the utility, and for an ANSI 9S base meter for example, a worker may install the meter in any ANSI 9S socket. If the electric connection between the meter and the power lines at that particular installation correspond to the preprogrammed selected instruction set, then the worker need not take any further action with respect to proper installation. If the particular installation does not correspond to the preprogrammed selected instruction sets, the worker may then select the appropriate instruction set or sets by transmitting a select signal to the microcomputer via the optical port. The microcomputer then transmits the command signal to the DSP instructing the DSP to execute a particular preloaded instruction set corresponding the electric circuit at the installation.
With the above described meter configuration, and rather than requiring a utility to store many different meters in inventory, only two sets of meters need be on hand for socket based applications, for example. These meters are readily and easily configurable so that accurate metering is performed at each installation.